1Universitätsklinikum Münster Klinik für Kardiologie II - Rhythmologie Münster, Deutschland; 2Universitätsklinikum Münster Herz- und Thoraxchirurgie Münster, Deutschland
Objective and Background: To assess the risk of failed defibrillation of ventricular fibrillation (VF) with the totally subcutaneous implantable cardioverter defibrillator (S-ICD), the PRAETORIAN Score has been proposed. We aimed at validating this score in a large daily-life S-ICD collective and at identifying potential predictors of defibrillation failure.
Methods and Results: An analysis of 398 consecutive patients after S-ICD implantation in our center was performed. Patients were mostly male (n=268; 67.3%) with a mean age of 42.4±15.9 years and a BMI of 25.9±4.8 kg/m2. Successful intraoperative defibrillation testing (DFT) with the first ICD shock was observed in 264 (66.3%) patients. Most of the remaining patients were successfully tested with the second (reverse polarity) or third (80 instead of 65 Joules of shock energy) intraoperative shock (127; 31.9%), only in 7 patients, no successful shock was applied. In these patients, S-ICD repositioning was performed until successful testing. The majority (n=88, 65.7%) of defibrillation failures happened before 2015 with the first S-ICD generation. The PRAETORIAN score proved to be an independent predictor for defibrillation failure (OR 1.007, CI 1.003, 1.011, p 0.001). BMI was not predictive in our multivariate analysis, but presence of a hypertrophic cardiomyopathy (OR 2.6; CI 1.3, 4.4, p= 0.004) was predictive for at least one unsuccessful defibrillation in a multivariate regression analysis.
Conclusion: The PRAETORIAN score was found to be a useful and valid predictive tool for S-ICD defibrillation success. Correct electrode placement appeared to be more important than increased BMI for prediction of defibrillation failure. Patients with hypertrophic cardiomyopathy were at increased risk for defibrillation failure.